urobilin

Pronunciation: yur'o-bi'lin

Definition: A uroporphyrin; an acyclic tetrapyrrole that is one of the natural breakdown products of heme via choleglobin, verdohemochrome, biliverdin, bilirubin, and d-urobilinogen; a urinary pigment that gives a varying orange-red coloration to urine according to its degree of oxidation.